LTC2421CMS datasheet(26/32 Pages) LINER

26 / 32 page

LTC2421/LTC2422

24212f

APPLICATIO S I FOR ATIO

nummeas = nummeas + c1%

LOCATE 2, 2: PRINT "Scan#="; nummeas; " "; DATE$; " "; TIME$;

OUT mcr%, c0%: 'Initialize SCLK=0

k1 = km: d2400 = 0: chan% = c0%: signneg% = c0%

FOR bita% = 31 TO 0 STEP -1: v31 = 1

148 GOSUB 2200: v31 = v31 + 1

150 IF bita% = 31 THEN GOTO 152 ELSE 156

152 IF dfrm% = c0% THEN GOTO 156

155 IF v31 > 2 THEN LOCATE 16, 16: OUT port, c0%: PRINT "waiting for eoc":

IF v31 < 20000 THEN IF dfrm% = c1% THEN GOTO 148

IF dfrm% = 1 THEN LOCATE 17, 16: PRINT "Timed out on EOC,not fatal"

FOR bs = 1 TO 32: ' never got an eoc => clock it 32 times

GOSUB 2000: NEXT bs: GOTO 1800

156 LOCATE 16, 16: PRINT"

": GOSUB 2000

IF bita% = 30 THEN 161 ELSE 171 ' CHANNEL BIT !!!!!!!!!!!!!!!

161 IF dfrm% = c1% THEN chan% = c1%: ch1% = c0%

IF dfrm% = c0% THEN chan% = c0%: ch1% = ch1% + c1%

IF ch1% > c4% THEN GOSUB 3700: ch1% = c1%

171 IF bita% = 29 THEN IF dfrm% = c0% THEN signneg% = c1%: ' NEG

IF bita% <= 28 THEN d2400 = d2400 + (dfrm% * k1): k1 = k1 / c2%

NEXT bita%: k1 = 1: digin% = c0%: 'MATH BELOW

1600 PPM = (d2400 / km) * kn: rw% = 6: hz% = (chan% * 20) + 1

IF signneg% = c1% THEN 1700 ELSE 1705

1700 IF d2400 <> c0% THEN PPM = (PPM - 2000000)

1705 LOCATE rw%, hz%: PRINT PPM; " "; : LOCATE rw%, hz% + 11:

PRINT "PPM";

LOCATE rw% + 1, (chan% * 20) + 1: GOSUB 3800: 'THIS WORKS!

1800 LOOP WHILE INKEY$ = "": REM Works with "DO"

GOTO 5000 ’rem END!!-------------- Subs follow !!----------------!!!

1900 ’ESSENTIAL INITIALIZATIONS

REM set some constants, since they can be accessed much faster

LET c128% = 128: c64% = 64: c32% = 32: c16% = 16: c8% = 8: c4% = 4

LET c3% = 3: c2% = 2: c1% = 1: c0% = 0: km = (2 ^ 30) - 1: kn = 1000000

IF cport = 2 THEN OPEN "COM2:300,N,8,1,CD0,CS0,DS0,OP0,RS" FOR

RANDOM AS #1: port = (&H2F8)

IF cport = 1 THEN OPEN "COM1:300,N,8,1,CD0,CS0,DS0,OP0,RS" FOR

RANDOM AS #1: port = (&H3F8)

LOCATE 5, 21: PRINT "CHANNEL 1": LOCATE 5, 2: PRINT "CHANNEL 0"

FOR n% = port TO port + 7: OUT n%, 0: NEXT n%: ’Init UART regs

CLOSE #1: DEF SEG = 0: RETURN ’--------------------------------------

2000 ’SUB read MSR AND RETURN data dfrm% INTERFACE

x3% = INP(msr%) AND c16%: OUT mcr%, c1%

GOSUB 3000: OUT mcr%, c0%

2040 IF x3% = c16% THEN dfrm% = c1% ELSE dfrm% = c0%

OUT mcr%, c0%: RETURN ’---------------------------------------------

2200 ’SUB READ THE DATA BIT dfrm% does NOT change sclock

x3% = INP(msr%) AND C16%: GOTO 2040: RETURN’----------------

3000 REM delay sub !!!!!!!!!!

FOR n8% = 0 TO 1: OUT port, c0%: NEXT n8%: RETURN: ’----------

3700 FOR n = 6 TO 9: LOCATE n, 20

PRINT "

": NEXT n: RETURN’---------------------------

3800 ’SUB to convert PPM into Volts and print it

v = PPM * (5 / 1000000): v1 = v * 1000000: hz% = (chan% * 20) + 12

IF v <= .1 THEN PRINT v1; "

"; : LOCATE rw% + 1, hz%: PRINT "uV "

IF v > .1 THEN PRINT v; " "; : LOCATE rw% + 1, hz%: PRINT "Volts";

RETURN’----------------------------------------------------------------

4970 PRINT "ERROR !!!!!!!!!!!!!!!"

5000 PRINT : LOCATE 18, 1: PRINT "Ending!!": PRINT "Hit any key to exit."

PRINT "Start ="; timestart$; " End = "; TIME$; " # samples ="; nummeas

CLOSE #1: END

Single Ended Half-Bridge Digitizer

with Reference and Ground Sensing

Sensors convert real world phenomena (temperature, pres-

sure, gas levels, etc.) into a voltage. Typically, this voltage

is generated by passing an excitation current through the

sensor. The wires connecting the sensor to the ADC form

parasitic resistors RP1 and RP2. The excitation current also

flows through parasitic resistors RP1 and RP2, as shown in

Figure 29. The voltage drop across these parasitic resis-

tors leads to systematic offset and full-scale errors.

In order to eliminate the errors associated with these para-

sitic resistors, the LTC2421/LTC2422 include a full-scale

set input (FSSET) and a zero-scale set input

(ZSSET). As shown in Figure 30, the FSSET pin acts as a

zero current full-scale sense input. Errors due to parasitic

LTC2421CMS Datasheet(PDF) 26 Page - Linear Technology

LTC2421CMS Datasheet(HTML) 26 Page - Linear Technology

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

Datasheet Descarga

Enlace URL